//函数声明法
function add(n1, n2) {
    return n1 + n2;
}
console.log(add(1, 2));
//函数表达式法
var subtract = function (n1, n3) {
    return n1 + n3;
};
console.log(subtract(2, 3));
//箭头函数法  完全支持ES6
var multiplication = function (n1, n2) {
    return n1 + n2;
};
console.log(multiplication(2, 8));
